Lens barrels of zoom lenses and continuously variable focus lens need to be accurately positioned on a continuous basis. This limits design approaches and can add cost and complexity. A two position lens requires accurate positioning in only those two positions. In-between positions are unimportant. U.S. Pat. No. 4,725,864 teaches a camera that can be limited to two focal lengths, but does not take advantage of this. The mechanism disclosed shows a lens system that is the same as for a continuously variable lens embodiment.
U.S. Pat. No. 6,466,740 teaches a one-time-use camera that is switchable between two focus positions. The camera has a lens holder that is continuously biased against a cam surface that closely resembles those of the continuously variable focusing mechanisms disclosed in U.S. Pat. Nos. 5,289,320; 5,613,168; and 3,220,308. The mechanism is relatively simple, but lacks some versatility, since the lens must rotate to follow a cam curve between positions.
It would thus be desirable to provide an improved camera assembly, in which a simple mechanism with a small number of parts provides lens positioning in two opposed positions.